Conveniently, receiving holes are formed by tie rods used during the pouring of concrete walls to hold wall pre-forms in spaced alignment. However, the holes left by the tie rods are generally tapered and therefore are wider on one wall surface than the opposing wall surface. This is problematic because most wall anchors currently used in construction are designed to fit into holes which have a relatively constant diameter such as holes formed by drilling. They have a limited expansion range which is not designed to fit into a tapered hole. As a result, such anchors are more likely to fail particularly when placed into the wide end of a tapered hole.
One such type of anchor is characterized by a plunger having a flared distal end that is pulled to compress a coiled spring during installation. Upon release, the spring biases the plunger into engagement with the walls of a pre-drilled hole. Fresh holes must be drilled every day to hold the anchors since the springs cannot be relied on to remain secure if left overnight.
Another problem which arises in the construction of high rise buildings is that anchors are required to enable workers to work as safely as possible at the earliest possible opportunity, sometimes while the concrete is still green and has not fully set. Because the load from most anchors is applied to the outside surface, the surface of the concrete may crumble particularly if the concrete hasn't fully set.
Common anchors for roof retaining applications in mining are not specifically designed with an attachment loop to secure objects like a safety strap and are not convenient for use in construction where a plurality of anchors are required at once on every floor of the building as the construction progresses. In addition, safety straps usually need to be removed from the building walls once the exterior wall panels and windows have been installed and unless the anchors are removable, the safety straps are often sacrificed and simply cut, for example when attached to vertical reinforcement bars disposed in the concrete walls.
Therefore, there exists a need for an improved anchor bolt which will at least in part address some of the aforementioned problems.